PDF and Firefox Issues

Hello everyone,

Hopefully someone can help me out with this annoying issue. Basically, we have some PDFs that won’t load on our site, only in Firefox.

We can load smaller files just fine. We can also load the PDF in any other browser (including IE) just fine, only Firefox has the issue.

We can also load these big files in a different directory (which is set up in IIS as a different site) in Firefox with no problem.

Anyone have any ideas of something we might have missed?


How do you trigger that load? With a link? What’s code for the link? When you say ‘won’t load’, what do you mean? What does happen?

very strange error. try deleting problem directory and try to create it with same name and see what happen

We’re using what should be a direct link to the file (ex: http://mysite.com/myfolder/mypdf.pdf).

It causes one of three issues:

  • Loads partially then freezes Firefox (the first page is visible).
  • Loads the PDF area but not the page, then freezes Firefox.
  • Loads a white page and freezes Firefox.

We’ve narrowed down the issue to the following scenario:

  • Only Firefox
  • Only using Adobe Acrobat Reader plugin (Foxit Reader plugin works)
  • Only larger files (seems to be around 700kb limit)
  • Only in that directory.

Unfortunately we can’t just delete the problem directory. It is actually set up as it’s own “site” in IIS as well.

Just in case anyone runs into this problem and comes across this article, I think we found the solution. This thread describes the problem: http://forums.iis.net/p/1161071/1921786.aspx#1921786

Apparently there is a hotfix here: http://support.microsoft.com/kb/979543

The gist of the problem is essentially Windows Server 2008 R2 changed how they served certain types of files, which makes them not always transmit their media type, which confuses Adobe Reader. Apparently new versions of Adobe Reader don’t have the issue as well (but you can’t always count on your clients to fix the problem, hence the hotfix).

Most… annoying… bug… ever. =p